class People{
   int age,leg = 2,hand = 2;
   protected void showPeopleMess(){
       System.out.printf("%d岁,%d只脚,%d只手\t",age,leg,hand);
   }
}
 
class Student extends People{
      int number;
      void tellNumber(){
          System.out.printf("学号 :%d\t",number);
      }
      int add (int x,int y){
          return x+y;
      }
}

class UniverStudent extends Student {
     int multi (int x ,int y){
         return x*y;
     }
}


public class Example5_1{
    public static void main(String arg[]){
      Student zhang =  new Student();
      zhang.age = 17;
      zhang.number = 100101;
      zhang.showPeopleMess();
      zhang.tellNumber();
      int x = 9,y = 29;
      System.out.print("会做加法");
      int result = zhang.add(x,y);
      System.out.printf("%d+%d=%d\n",x,y,result);
      UniverStudent geng = new UniverStudent();
      geng.age = 21;
      geng.number = 6609;
      geng.showPeopleMess();
      geng.tellNumber();
      System.out.print("会做加法");
      result = geng.add(x,y);
      System.out.printf("%d+%d=%d\n",x,y,result);
      System.out.print("会做乘法");
      result = geng.multi(x,y);
      System.out.printf("%d*%d=%d\n",x,y,result);

   }
}




      

















